[R] test of spatial dependence?? - ask an ecologist?

[Roger Bivand]

On Wed, 6 Dec 2006, Xu Yuan wrote:

> Thanks David and Milton for replies. No, I don't have the coordiates.
> In other words, my data are not point data. But I think there is a way
> to test of spatial dependence for areal data or lattice data. In this
> case, the variable of interest is typically the average value of an
> area instead of a point. Do you how to do this?

But do you know where the areas are in relation to each other? Does the 
spatialCovariance package help?

Roger

> 
>  Thank you.
>  Xu
> 
> On 12/6/06, Milton Cezar Ribeiro <milton_ruser at yahoo.com.br> wrote:
> >
> > I never used it, but I beleave that it is a job for "mantel.rtest()" available on "ade4" package.
> >
> > In fact Farrar are right, you will neet the XY coordinates. Give a look at "Legendre & Legendre" text book.
> >
> > HTH,
> >
> > Miltinho
> > Brazil
> >
> > David Farrar <dfarrar at newrvana.com> escreveu:
> >
> >
> > In addition to the 25 numbers, I assume you have coordinates of each field.
> > Otherwise, I don't understand what you are trying to do. I think ecologists like to use a test due to Mantel in this situation.
> >
> > The prefix "auto" means "self," of course, the idea being that measurements of the same variable under different conditions are correlated. I guess this would be a case of "autodependence." For correlation versus dependence, check your  intro stats book.
> >
> > de nada,
> > X'X
> >
> > Farrar
> >
> >
> > Xu Yuan wrote:
> > hello R-friends,
> >
> > I am a R beginner and try to ask a basic question:
> >
> > How to test the spatial dependence of a column of data? for example, I have
> > 25 agricultural fields, and I measure the average slope (%) or pH for each
> > field. All I have is 25 numbers.
> >
> > PS, could someone confirm that "spatial dependence" is equivalent to
> > "spatial correlation" or "spatial autocorrelation" or not.
> >
> > Thank you very much.
> > XY
> >
> > [[alternative HTML version deleted]]
> >
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> ______________________________________________
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> 

-- 
Roger Bivand
Economic Geography Section, Department of Economics, Norwegian School of
Economics and Business Administration, Helleveien 30, N-5045 Bergen,
Norway. voice: +47 55 95 93 55; fax +47 55 95 95 43
e-mail: Roger.Bivand at nhh.no